There is, indeed, one passage of the Encyclical in which Pope Leo seems to allude to the Single Tax, or to some similar proposal. He expresses his amazement at those persons who "assert that it is right for private persons to have the use of the soil and its various fruits, but that it is unjust for any one to possess outright either the land on which he has built, or the estate which he has brought under cultivation. But those who deny these rights do not perceive that they are defrauding man of what his own labour has produced. For the soil which is tilled and cultivated with toil and skill utterly changes its conditions: it was wild before, now it is fruitful; was barren, but now brings forth in abundance. That which has thus altered and improved the land becomes so truly a part of itself as to be in great measure indistinguishable and inseparable from it. Is it just that the fruit of a man's own labour should be possessed and enjoyed by any one else? As effects follow their cause, so is it just and right that the results of labour should belong to those who have bestowed their labour."
In this passage we find two principal statements: first, that those persons are in error who declare full private ownership of land to be unjust; and, second, that it is wrong to deprive a man of the improvements which he makes in the soil. Now the first of these propositions does not touch the Single Tax system as such; it only condemns the assertion of Henry George that private ownership is essentially unjust. It is directed against one of the arguments for the system, not against the system itself. More specifically, it is a refutation of an argument against private land ownership, rather than a positive attack upon any other system. It could be accepted by any Single Taxer who does not agree with Henry George that the present system is essentially unjust. The second proposition does not apply to the Single Tax system at all; for the latter would concede to the individual holder the full ownership and benefit of improvements; and it could easily be so administered as to protect him against injury in any case in which improvement values were not exactly and clearly distinguishable from land values.